X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Mon, 11 Apr 2011 07:56:57 -0400 Message-ID: X-Original-Return-Path: Received: from hrndva-omtalb.mail.rr.com ([71.74.56.122] verified) by logan.com (CommuniGate Pro SMTP 5.4c3j) with ESMTP id 4941537 for lml@lancaironline.net; Sat, 09 Apr 2011 11:50:12 -0400 Received-SPF: none receiver=logan.com; client-ip=71.74.56.122; envelope-from=Wolfgang@MiCom.net X-Original-Return-Path: X-Authority-Analysis: v=1.1 cv=qyUSAyc82z9xLljZQc9ErY9Tl2GSEfqK/XYZS35I9d8= c=1 sm=0 a=ttCsPuSJ-FAA:10 a=MHZY6FYWMEQOp7S43i2QIw==:17 a=5FIZSGrRAAAA:8 a=rTjvlri0AAAA:8 a=CjxXgO3LAAAA:8 a=Ia-xEzejAAAA:8 a=ksrBkpnIz885mUQn638A:9 a=50PancS06Xm3Bbqv1jcA:7 a=wPNLvfGTeEIA:10 a=wR8WdYEwGqoA:10 a=Dr9Wx-Q63l4A:10 a=rC2wZJ5BpNYA:10 a=EzXvWhQp4_cA:10 a=OYXqS0cQ1erL1bHa0ikA:9 a=pSJH5408Jit6ZrIFd8oA:7 a=MHZY6FYWMEQOp7S43i2QIw==:117 X-Cloudmark-Score: 0 X-Originating-IP: 74.218.201.50 Received: from [74.218.201.50] ([74.218.201.50:1100] helo=Lobo) by hrndva-oedge02.mail.rr.com (envelope-from ) (ecelerity 2.2.3.46 r()) with ESMTP id 43/64-08375-F0080AD4; Sat, 09 Apr 2011 15:49:36 +0000 X-Original-Message-ID: <006501cbf6cd$b6791bf0$6401a8c0@Lobo> From: "Wolfgang" X-Original-To: Subject: Re: LNC2 Gear Hydraulics X-Original-Date: Sat, 9 Apr 2011 11:49:29 -0400 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0062_01CBF6AC.2F298890" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.2180 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2180 This is a multi-part message in MIME format. ------=_NextPart_000_0062_01CBF6AC.2F298890 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable When I first got into this problem with the hydraulic pumps last year, I = had a few conversations with the product manager of the Oildyne 108 = pump. There have been many changes in it's production life and one of = them was to make the spool symmetrical and have the relief circuit the = same both ways. Wolfgang -------------------------------------------------------------------------= ------- Wolfgang, Yes, I have considered this. The spool with O-ring is a very tight = fight. While I have not tried to measure the force to move it, I would = estimate something over 50 g's to move it (I'll measure this the next = time I have a pump opened up) Could it be that a pump somehow ended up = mounted such that it was subjected to some resonant frequency? Seems = like a remote possibilty given all the variables and the mass of the = pump. How about wear and tear? Perhaps sitting dry and idle for ten = years would do it. A missing O-ring or a spool that doesn't utilize an = O-ring would allow the spool to move very easily. Parker does make = spools that don't even have O-rings. Did these end up getting installed = by chance? Based on reports from the LML, the behavior seems to be rather binary. = On the one hand we have planes with over 1000 hours and more than ten = years of service that have never once had the spool move off the poppet. = On the other hand, we have planes with circuits that lock up right out = of the box (put into service). This leads me to believe there is a difference in configuration. The = easiest way to verify this is to simply open up a pump that is known to = lock up hi and low circuits simultaneously. While I have opened up several pumps (primarily to flip around spool = valves), I have not yet worked on one that had this lock up issue. I am = optimistic the difference will be quite obvious upon inspection. =20 Chris Zavatson N91CZ 360std www.N91CZ.net Sent from my iPad On Apr 7, 2011, at 11:53 AM, "Wolfgang" wrote: Chris, have you considered what effect airframe vibration has on the = position of the spool in the pump and the problem in general ? Wolfgang -------------------------------------------------------------------------= ----- From: Chris =20 Sender: =20 Subject: Re: [LML] Re: LNC2 Gear Hydraulics=20 Date: Wed, 06 Apr 2011 07:38:35 -0400=20 To: lml@lancaironline.net=20 =20 =20 I would like to extend the offer to the whole group. I think = the entire community would benefit from understanding why some pumps are = allowing the system to lock up. If anyone has a pump that exhibits this = behavior and could part with it for a week, I am willing to check it out = on the test stand and examine the internal configuration. Chris Zavatson N91CZ 360std www.N91CZ.net=20 ------=_NextPart_000_0062_01CBF6AC.2F298890 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
When I first got into this problem with = the=20 hydraulic pumps last year, I had a few conversations with the product = manager of=20 the Oildyne 108 pump. There have been many changes in it's production = life and=20 one of them was to make the spool symmetrical and have the relief = circuit the=20 same both ways.
 
Wolfgang
Wolfgang,
Yes, I have considered this.  The spool with O-ring is a very = tight=20 fight.  While I have not tried to measure the force to move it, I = would=20 estimate something over 50 g's to move it (I'll measure this the next = time I=20 have a pump opened up)  Could it be that a pump somehow ended up = mounted=20 such that it was subjected to some resonant frequency?  Seems like = a remote=20 possibilty given all the variables and the mass of the pump.   =  How=20 about wear and tear?  Perhaps sitting dry and idle for ten years = would do it.=20  A missing O-ring or a spool that doesn't utilize an O-ring would = allow the=20 spool to move very easily.  Parker does make spools that don't even = have=20 O-rings.  Did these end up getting installed by = chance?

Based on reports from the LML, the behavior = seems to be=20 rather binary.  On the one hand we have planes with over 1000 hours = and=20 more than ten years of service that have never once had the spool move = off the=20 poppet.  On the other hand, we have planes with circuits that lock = up right=20 out of the box (put into service).
This leads me to believe there is a difference = in=20 configuration.  The easiest way to verify this is to simply open up = a pump=20 that is known to lock up hi and low circuits = simultaneously.

While I have opened up several pumps (primarily to flip around = spool=20 valves), I have not yet worked on one that had this lock up issue. =  I am=20 optimistic the difference will be quite obvious upon inspection. =  

Chris Zavatson
N91CZ
360std


Sent from my iPad

On Apr 7, 2011, at 11:53 AM, "Wolfgang" <Wolfgang@MiCom.net>=20 wrote:

Chris, have you considered what = effect airframe=20 vibration has on the position of the spool in the pump and the problem = in=20 general ?
 
Wolfgang
<= /TR>
From: Chris <chris_zavatson@yahoo.com= >
Sender: <marv@lancaironline.net>=
Subject: Re: [LML] Re: LNC2 Gear=20 Hydraulics
Date: Wed, 06 Apr 2011 07:38:35=20 -0400
To: lml@lancaironline.net
I would like to extend the offer to the whole group. =  I think=20 the entire community would benefit from understanding why some = pumps are=20 allowing the system to lock up.  If anyone has a pump that = exhibits=20 this behavior and could part with it for a week, I am willing to = check=20 it out on the test stand and examine the internal = configuration.

Chris Zavatson
N91CZ
360std
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